Method for Off-Gasing Purified Gases in a Melting Device

ABSTRACT

A method for producing a purified product stream is disclosed. A process stream is provided to a screw compressor, the process stream comprising a contact liquid stream and a product stream, wherein the product stream comprises a solid portion. The process stream is passed through the screw compressor and into a melting device. The solid portion of the product stream is melted in the melting device to a temperature and a pressure such that a portion of the product stream vaporizes, forming a purified product stream, and vaporization of the contact liquid stream into the purified product stream is essentially prevented. A restricted outlet is provided to an upper portion of the vessel. The restricted outlet is proportionally controlled such that the pressure and the temperature is maintained as the purified product stream passes through the restricted outlet. In this manner, the purified product stream is produced.

This invention was made with government support under DE-FE0028697 awarded by The Department of Energy. The government has certain rights in the invention.

BACKGROUND Field of the Invention

This invention relates generally to the field of separations. More particularly, we are interested in separating acid gases, such as carbon dioxide, from cryogenic liquids.

Related Technology

The art of separations is well developed for the majority of standard applications. However, cryogenic separations are still a relatively new field and many difficult separation problems still exist. One of these is separating carbon dioxide and other acid gases from various carrier gases. Scrubbing of these carrier gases by various organic solvents produces slurries that can be compressed to further produce liquid mixtures of carbon dioxide and the solvents. However, separating these solvents from the carbon dioxide at high purity is energy intensive and cost prohibitive. The ability to effectively separate liquid carbon dioxide and other liquefied acid gases from carrier solvents is required.

Venting of gases produced from liquid mixtures is used in every industry where a gas or vapor may volatilize and thereby over-pressurize a vessel, pipe, or other equipment. However, using this tendency to purposefully make a purified product gas stream from a multi-component liquid mixture is not found. Because these gases and vapors are volatized from the liquid mixture as a byproduct and not under carefully tailored conditions, the vapors contain at least a portion of non-product components. The ability to produce vent gases and vapors with essentially no non-product components is required.

United States patent publication number 5974829, to Novak, et al., teaches a method for carbon dioxide recovery from a feed stream. At one point, the compressed flow is passed through a distillation column and separated into a vent gas containing some carbon dioxide and a high purity bottom liquid carbon dioxide stream. The present disclosure differs from this disclosure in that the vent gas is a mixture, not a pure carbon dioxide stream. This disclosure is pertinent and may benefit from the methods disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.

SUMMARY

A method for producing a purified product stream is disclosed. A process stream is provided to a screw compressor, the process stream comprising a contact liquid stream and a product stream, wherein the product stream comprises a solid portion. The process stream is passed through the screw compressor and into a melting device. The solid portion of the product stream is melted in the melting device to a temperature and a pressure such that a portion of the product stream vaporizes, forming a purified product stream, and vaporization of the contact liquid stream into the purified product stream is essentially prevented. A restricted outlet is provided to an upper portion of the vessel. The restricted outlet is proportionally controlled such that the pressure and the temperature is maintained as the purified product stream passes through the restricted outlet. In this manner, the purified product stream is produced.

The product stream may comprise carbon dioxide, nitrogen oxide, sulfur dioxide, nitrogen dioxide, sulfur trioxide, hydrogen sulfide, hydrogen cyanide, water, condensed hydrocarbons, or combinations thereof.

The screw compressor may comprise a connection to the melting device above a level of the process stream. The screw compressor may comprise a connection to the melting device below a level of the process stream.

The restricted outlet may comprise a valve, a compressor, a pump, or a combination thereof. The vessel further may comprise a pressure sensor, an output of the pressure sensor transmitting the pressure. The proportionally controlling step may be accomplished by opening or closing the restricted outlet proportional to the pressure. The vessel may comprise a level sensor, an output of the level sensor transmitting a liquid level. The liquid level of the process stream in the melting device may be maintained by the output of the level sensor.

A controller may be provided, the controller receiving the output of the pressure sensor and the output of the level sensor and controlling the restricted outlet and the liquid level.

The melting device may comprise a shell and tube style heat exchanger, plate style heat exchanger, plate and frame style heat exchanger, plate and shell style heat exchanger, spiral style heat exchanger, plate fin style heat exchanger, or combinations thereof.

The contact liquid stream may comprise any compound or mixture of compounds with a freezing point below the temperature at which the product stream solidifies. The contact liquid stream may comprise water, brine, hydrocarbons, liquid ammonia, liquid carbon dioxide, other cryogenic liquids, other hydrocarbons, and combinations thereof. The contact liquid stream may comprise 1,1,3-trimethylcyclopentane, 1,4-pentadiene, 1,5-hexadiene, 1-butene, 1-methyl-1-ethylcyclopentane, 1-pentene, 3,3,3,3-tetrafluoropropene, 3,3-dimethyl-1-butene, 3-chloro-1,1,1,2-tetrafluoroethane, 3-methylpentane, 3-methyl-1,4-pentadiene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-methylpentane, 5-methyl-1-hexene, 5-methyl-1-pentene, 5-methylcyclopentene, 5-methyl-trans-2-pentene, bromochlorodifluoromethane, bromodifluoromethane, bromotrifluoroethylene, chlorotrifluoroethylene, cis 3-hexene, cis-1,3-pentadiene, cis-2-hexene, cis-2-pentene, dichlorodifluoromethane, difluoromethyl ether, trifluoromethyl ether, dimethyl ether, ethyl fluoride, ethyl mercaptan, hexafluoropropylene, isobutane, isobutene, isobutyl mercaptan, isopentane, isoprene, methyl isopropyl ether, methylcyclohexane, methylcyclopentane, methylcyclopropane, n,n-diethylmethylamine, octafluoropropane, pentafluoroethyl trifluorovinyl ether, propane, sec-butyl mercaptan, trans-2-pentene, trifluoromethyl trifluorovinyl ether, vinyl chloride, bromotrifluoromethane, chlorodifluoromethane, dimethyl silane, ketene, methyl silane, perchloryl fluoride, propylene, vinyl fluoride, or combinations thereof.

The process stream may comprise a solid portion comprising particulates, mercury, other heavy metals, condensed organics, soot, inorganic ash components, biomass, salts, water ice, frozen acid gases, other impurities common to a vitiated flow, the producer gases, or the other industrial flows, or combinations thereof.

The purified product stream may be provided to a pure liquid product stream to condense the purified product stream into the pure liquid product stream. The purified product stream may be cooled in a heat exchanger, producing a cooled purified product stream. The cooled purified product stream may be compressed into a liquid phase, producing a liquefied pure product stream. The liquefied pure product stream may be passed through a heat exchanger.

The screw compressor may comprise porous walls through which a portion of the contact liquid stream is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through use of the accompanying drawings, in which:

FIG. 1 shows a method for producing a purified product stream.

FIG. 2 shows a cross-section of a screw compressor and melter for producing a purified product stream.

FIG. 3 shows a cross-section of a screw compressor and melter for producing a purified product stream.

FIG. 4 shows an expanding pipe assembly for producing a purified product stream.

DETAILED DESCRIPTION

It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the invention, as represented in the Figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of certain examples of presently contemplated embodiments in accordance with the invention.

Referring to FIG. 1, a method for producing a purified product stream is shown at 100, as per one embodiment of the present invention. A process stream, comprising a contact liquid stream and a product stream, the product stream comprising a solid portion, is provided to a screw compressor 101. The process stream is passed through the screw compressor into a melting device 102. The solid portion of the product stream is melted to a temperature and a pressure 103. A portion of the product stream vaporizes, forming a purified product stream 104. A restricted outlet is provided to an upper portion of the vessel and is proportionally controlled such that the pressure is maintained, the pressure essentially preventing vaporization of the contact liquid stream 105. The purified product stream is passed through the restricted outlet 106. In this manner, the purified product stream is produced. In some embodiments, the screw compressor further comprises porous walls through which a portion of the contact liquid stream is removed.

Referring to FIG. 2, a cross-section of a screw compressor and melter for producing a purified product stream is shown at 200, as per one embodiment of the present invention. Screw compressor 202 comprises screw inlet 208, filtering walls 216, and screw outlet 210. Melter 204 receives material through screw outlet 210 and comprises gas outlet 212, liquid outlet 214, and exchanger 206. Carbon dioxide slurry 220, comprising a contact liquid stream and a combination of carbon dioxide liquid and carbon dioxide solids, is passed through screw inlet 208 and is compressed through screw compressor 202, with a portion of the contact liquid stream pushed through filter walls 216. The remainder of process stream 220 passes into melter 204 as melter feed stream 222. Melter feed stream 222 is heated, melting the solid carbon dioxide, causing a portion of the carbon dioxide to vaporize as carbon dioxide product stream 224, with the remainder becoming product liquid 226. The contact liquid is essentially prevented from vaporizing at the pressure in the melter. Product liquid 226 leaves through melter outlet 214.

Referring to FIG. 3, a cross-section of a screw compressor and melter for producing a purified product stream is shown at 300, as per one embodiment of the present invention. Screw compressor 302 comprises screw inlet 308, filtering walls 316, and screw outlet 310. Melter 304 receives material through screw outlet 310 and comprises gas outlet 312, liquid outlet 314, exchanger 306, level sensor 18, first pressure sensor 330, and second pressure sensor 332. Carbon dioxide slurry 320, comprising a contact liquid stream and a combination of carbon dioxide liquid and carbon dioxide solids, is passed through screw inlet 308 and is compressed through screw compressor 302, with a portion of the contact liquid stream pushed through filter walls 316. The remainder of process stream 320 passes into melter 304 as melter feed stream 322. Melte feed stream 322 is heated, melting the solid carbon dioxide, causing a portion of the carbon dioxide to vaporize as carbon dioxide product stream 324, with the remainder becoming product liquid 326. The contact liquid is essentially prevented from vaporizing at the pressure in the melter. Product liquid 326 leaves through melter outlet 314. The pressure is maintained and gas outlet 312 is controlled by utilizing the pressure output of first pressure sensor 330 to proportionally control the opening or closing of gas outlet valve 312. Outputs from second pressure sensor 332 and level sensor 318 are used to maintain the liquid level. In some embodiments, the liquid level is maintained below the level of screw outlet 310.

Referring to FIG. 4, an expanding pipe assembly for producing a purified product stream is shown at 400, as per one embodiment of the present invention. Expanding pipe assembly 402 comprises an inlet pipe 404, an expanding section 406, an expanded section 408, a gas outlet valve 410 with valve actuator 412, pressure sensor 414, and pipe outlet 416. The pipes are all wrapped in heat tape (not shown for clarity). Process stream 420, comprising a contact liquid stream and a product stream, the product stream comprising a solid portion, is provided from a screw compressor (not shown) to inlet pipe 404. Process stream 420 is expanded through expanding section 406 into expanded section 408 and the solid portion melted by the heat tape. A portion of the product stream vaporizes, forming purified product stream 426. The pressure essentially prevents the vaporization of the contact liquid stream. The remainder of the process stream forms liquid product stream 422. The pressure is maintained by utilizing the pressure output of pressure sensor 414 to proportionally control the opening or closing of gas outlet valve 410. In some embodiments, a temperature sensor is provided to expanding pipe assembly 402 to provide further temperature control to process stream 420.

In some embodiments, the product stream further comprising carbon dioxide, nitrogen oxide, sulfur dioxide, nitrogen dioxide, sulfur trioxide, hydrogen sulfide, hydrogen cyanide, water, condensed hydrocarbons, or combinations thereof.

In some embodiments, the screw compressor comprises a connection to the melting device above a level of the process stream. In other embodiments, the screw compressor comprises a connection to the melting device below a level of the process stream.

In some embodiments, the restricted outlet comprises a valve, a compressor, a pump, or a combination thereof. In some embodiments, the vessel further comprises a pressure sensor, an output of the pressure sensor transmitting the pressure. In some embodiments, the proportionally controlling step is accomplished by opening or closing the restricted outlet proportional to the pressure. In some embodiments, the vessel further comprises a level sensor, an output of the level sensor transmitting a liquid level. In some embodiments, the liquid level of the process stream in the melting device is maintained by the output of the level sensor. In some embodiments, a controller is provided, the controller receiving the output of the pressure sensor and the output of the level sensor and controlling the restricted outlet and the liquid level.

In some embodiments, the melting device comprises a shell and tube style heat exchanger, plate style heat exchanger, plate and frame style heat exchanger, plate and shell style heat exchanger, spiral style heat exchanger, plate fin style heat exchanger, or combinations thereof.

In some embodiments, the contact liquid stream comprises any compound or mixture of compounds with a freezing point below the temperature at which the product stream solidifies. In some embodiments, the contact liquid stream comprises water, brine, hydrocarbons, liquid ammonia, liquid carbon dioxide, other cryogenic liquids, other hydrocarbons, and combinations thereof. In some embodiments, the contact liquid stream comprises 1,1,3-trimethylcyclopentane, 1,4-pentadiene, 1,5-hexadiene, 1-butene, 1-methyl-1-ethylcyclopentane, 1-pentene, 3,3,3,3-tetrafluoropropene, 3,3-dimethyl-1-butene, 3-chloro-1,1,1,2-tetrafluoroethane, 3-methylpentane, 3-methyl-1,4-pentadiene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-methylpentane, 5-methyl-1-hexene, 5-methyl-1-pentene, 5-methylcyclopentene, 5-methyl-trans-2-pentene, bromochlorodifluoromethane, bromodifluoromethane, bromotrifluoroethylene, chlorotrifluoroethylene, cis 3-hexene, cis-1,3-pentadiene, cis-2-hexene, cis-2-pentene, dichlorodifluoromethane, difluoromethyl ether, trifluoromethyl ether, dimethyl ether, ethyl fluoride, ethyl mercaptan, hexafluoropropylene, isobutane, isobutene, isobutyl mercaptan, isopentane, isoprene, methyl isopropyl ether, methylcyclohexane, methylcyclopentane, methylcyclopropane, n,n-diethylmethylamine, octafluoropropane, pentafluoroethyl trifluorovinyl ether, propane, sec-butyl mercaptan, trans-2-pentene, trifluoromethyl trifluorovinyl ether, vinyl chloride, bromotrifluoromethane, chlorodifluoromethane, dimethyl silane, ketene, methyl silane, perchloryl fluoride, propylene, vinyl fluoride, or combinations thereof.

In some embodiments, the process stream comprises a solid portion comprising particulates, mercury, other heavy metals, condensed organics, soot, inorganic ash components, biomass, salts, water ice, frozen acid gases, other impurities common to a vitiated flow, the producer gases, or the other industrial flows, or combinations thereof.

In some embodiments, the purified product stream is provided to a pure liquid product stream to condense the purified product stream into the pure liquid product stream. In some embodiments, the purified product stream is cooled in a heat exchanger, producing a cooled purified product stream. In some embodiments, the cooled purified product stream is compressed into a liquid phase, producing a liquefied pure product stream. In some embodiments, the liquefied pure product stream is passed through a heat exchanger.

In some embodiments, the screw compressor further comprises porous walls through which a portion of the contact liquid stream is removed. 

1. A method for producing a purified product stream comprising: providing a process stream to a screw compressor, the process stream comprising a contact liquid stream and a product stream, wherein the product stream comprises a solid portion; passing the process stream through the screw compressor and into a melting device; melting the solid portion of the product stream in the melting device to a temperature and a pressure such that: a portion of the product stream vaporizes, forming a purified product stream; and, vaporization of the contact liquid stream into the purified product stream is essentially prevented; providing a restricted outlet to an upper portion of the vessel; proportionally controlling the restricted outlet such that the pressure and the temperature is maintained as the purified product stream passes through the restricted outlet; whereby the purified product stream is produced.
 2. The method of claim 1, providing the product stream further comprising carbon dioxide, nitrogen oxide, sulfur dioxide, nitrogen dioxide, sulfur trioxide, hydrogen sulfide, hydrogen cyanide, water, condensed hydrocarbons, or combinations thereof.
 3. The method of claim 1, providing the screw compressor comprising a connection to the melting device above a level of the process stream.
 4. The method of claim 1, providing the screw compressor comprising a connection to the melting device below a level of the process stream.
 5. The method of claim 1, providing the restricted outlet comprising a valve, a compressor, a pump, or a combination thereof.
 6. The method of claim 5, providing the vessel further comprising a pressure sensor, an output of the pressure sensor transmitting the pressure.
 7. The method of claim 6, wherein the proportionally controlling step is accomplished by opening or closing the restricted outlet proportional to the pressure.
 8. The method of claim 7, providing the vessel further comprising a level sensor, an output of the level sensor transmitting a liquid level.
 9. The method of claim 8, further comprising maintaining the liquid level of the process stream in the melting device by the output of the level sensor.
 10. The method of claim 9, further comprising providing a controller, the controller receiving the output of the pressure sensor and the output of the level sensor and controlling the restricted outlet and the liquid level.
 11. The method of claim 1, providing the melting device comprising a shell and tube style heat exchanger, plate style heat exchanger, plate and frame style heat exchanger, plate and shell style heat exchanger, spiral style heat exchanger, plate fin style heat exchanger, or combinations thereof.
 12. The method of claim 1, providing the contact liquid stream comprising any compound or mixture of compounds with a freezing point below the temperature at which the product stream solidifies.
 13. The method of claim 1, providing the contact liquid stream comprising water, brine, hydrocarbons, liquid ammonia, liquid carbon dioxide, other cryogenic liquids, other hydrocarbons, and combinations thereof.
 14. The method of claim 1, providing the contact liquid stream comprising 1,1,3-trimethylcyclopentane, 1,4-pentadiene, 1,5-hexadiene, 1-butene, 1-methyl-1-ethylcyclopentane, 1-pentene, 3,3,3,3-tetrafluoropropene, 3,3-dimethyl-1-butene, 3-chloro-1,1,1,2-tetrafluoroethane, 3-methylpentane, 3-methyl-1,4-pentadiene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-methylpentane, 5-methyl-1-hexene, 5-methyl-1-pentene, 5-methylcyclopentene, 5-methyl-trans-2-pentene, bromochlorodifluoromethane, bromodifluoromethane, bromotrifluoroethylene, chlorotrifluoroethylene, cis 3-hexene, cis-1,3-pentadiene, cis-2-hexene, cis-2-pentene, dichlorodifluoromethane, difluoromethyl ether, trifluoromethyl ether, dimethyl ether, ethyl fluoride, ethyl mercaptan, hexafluoropropylene, isobutane, isobutene, isobutyl mercaptan, isopentane, isoprene, methyl isopropyl ether, methylcyclohexane, methylcyclopentane, methylcyclopropane, n,n-diethylmethylamine, octafluoropropane, pentafluoroethyl trifluorovinyl ether, propane, sec-butyl mercaptan, trans-2-pentene, trifluoromethyl trifluorovinyl ether, vinyl chloride, bromotrifluoromethane, chlorodifluoromethane, dimethyl silane, ketene, methyl silane, perchloryl fluoride, propylene, vinyl fluoride, or combinations thereof.
 15. The method of claim 1, providing the process stream further comprising a solid portion comprising particulates, mercury, other heavy metals, condensed organics, soot, inorganic ash components, biomass, salts, water ice, frozen acid gases, other impurities common to a vitiated flow, the producer gases, or the other industrial flows, or combinations thereof.
 16. The method of claim 1, further comprising providing the purified product stream to a pure liquid product stream to condense the purified product stream into the pure liquid product stream.
 17. The method of claim 1, further comprising cooling the purified product stream in a heat exchanger, producing a cooled purified product stream.
 18. The method of claim 17, further comprising compressing the cooled purified product stream into a liquid phase, producing a liquefied pure product stream.
 19. The method of claim 18, further comprising passing the liquefied pure product stream through a heat exchanger.
 20. The method of claim 1, providing the screw compressor further comprising porous walls through which a portion of the contact liquid stream is removed. 